Is wcore_display_teardown called only once, or when destroying each display?
If the latter, then it's not safe to call `mtx_destroy(&mutex)` on
`wcore_display_teardown`. Otherwise when wcore_display_init is called
next, wcore_display_init_once() will not be called a 2nd time, hence
mutex will stay invalid.
This should probably done at waffle_teardown.
BTW, if the mutex was initialized at waffle_init, then once_flag
wouldn't even be necessary.
Jose
On 24/03/15 16:56, Emil Velikov wrote:
C11 does not specify a static initializer, based on the idea that the
a mutex will be platform and/or implementation dependent. As such the
alternative solution is to initialize the mutex with call_once/mtx_init.
This will allow us to remove the transition hack, and in due time move
to the system's C11 threads implementation.
v2: Actually use call_once() to prevent the possibility of multiple
threads hitting the mtx_init() at the same time. Suggested by Jose.
Cc: Jose Fonseca <[email protected]>
Signed-off-by: Emil Velikov <[email protected]>
---
src/waffle/core/wcore_display.c | 19 ++++++++++++++++++-
src/waffle/core/wcore_display.h | 9 ++-------
2 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/src/waffle/core/wcore_display.c b/src/waffle/core/wcore_display.c
index 2feeeba..2cf0dcd 100644
--- a/src/waffle/core/wcore_display.c
+++ b/src/waffle/core/wcore_display.c
@@ -29,16 +29,25 @@
#include "wcore_display.h"
+static mtx_t mutex;
+
+static void
+wcore_display_init_once(void)
+{
+ mtx_init(&mutex, mtx_plain);
+}
+
bool
wcore_display_init(struct wcore_display *self,
struct wcore_platform *platform)
{
static size_t id_counter = 0;
- static mtx_t mutex = _MTX_INITIALIZER_NP;
+ static once_flag flag = ONCE_FLAG_INIT;
assert(self);
assert(platform);
+ call_once(&flag, wcore_display_init_once);
mtx_lock(&mutex);
self->api.display_id = ++id_counter;
mtx_unlock(&mutex);
@@ -52,3 +61,11 @@ wcore_display_init(struct wcore_display *self,
return true;
}
+
+bool
+wcore_display_teardown(struct wcore_display *self)
+{
+ assert(self);
+ mtx_destroy(&mutex);
+ return true;
+}
diff --git a/src/waffle/core/wcore_display.h b/src/waffle/core/wcore_display.h
index de6ca5e..6d95d98 100644
--- a/src/waffle/core/wcore_display.h
+++ b/src/waffle/core/wcore_display.h
@@ -56,10 +56,5 @@ wcore_display_init(struct wcore_display *self,
struct wcore_platform *platform);
-static inline bool
-wcore_display_teardown(struct wcore_display *self)
-{
- (void) self;
- assert(self);
- return true;
-}
+bool
+wcore_display_teardown(struct wcore_display *self);
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